1. Field of the Invention
The present invention generally relates to a label printer, and more particularly to a label printer which provides a plurality of printer units each capable of printing out a different label and which selects one or more of the printer units to print out labels.
2. Prior Art
Recently, it is likely to attach several kinds of labels on one commodity in super-markets and general markets. For example, the commodity is attached with an advertisement label (or a POP label) printed with characters such as "SPECIAL PRICE" and "ADVERTISED GOODS", in addition to a pricing label (or a weight label) printed with a price of the commodity calculated based on a measured weight thereof As such pricing label, several kinds of labels each size corresponding to the kind of each commodity are used.
In order to satisfy the above-mentioned condition, the following two methods can be employed.
(1) The market must use a plurality of label printers each independently corresponding to the kind of each label.
(2) Programs capable of printing out a plurality kinds of labels must be stored in one label printer, and the labels must be exchanged according to needs.
However, in the above (1) method, a plurality of label printers must be required, so that the costs of whole printer apparatus must be raised. In the above (2) method, it is burdensome to exchange the labels.
In order to solve the above problems, the present applicant has been proposed a measuring and printing apparatus in a Japanese Patent Unexamined Publication No. 60-161167. Such apparatus uses a label sheet in which two kinds of labels are attached on a mount in parallel and also has a thermal head the length of which corresponds to a width of such label sheet. Hence, this thermal head can simultaneously print out two kinds of labels.
However, the above-mentioned proposed apparatus suffers the following five new problems.
(a) The proposed apparatus uses the label sheet attached with two kinds of labels. Hence, when it is required to print out only one label, the proposed apparatus prints only one label. Therefore, another un-printed label must be wasted.
(b) Formation of the label sheet becomes complicated, so that such label sheet will raise the running cost of the proposed apparatus. In addition, it must be required to prepare many kinds of label sheets in response to the kind of the labels and the combination of the labels.
(c) The thermal head is required to have the size capable of simultaneously printing two kinds of labels. Hence, it must be difficult to print a label having a large size.
(d) In order to exchange the kind of the labels, the operator must exchange the set label sheet. Hence, it is burdensome for the operator to exchange the label sheet.
(e) In general, the label printer is designed to take the printed label off the mount and publish the printed label. Hence, the size of the label sheet must be limited so that lengths of the two labels can be equal to each other in a longitudinal direction of the label sheet.